Opportunity Crops: Forgotten Plants Hold Potential for a Healthy Diet

The 16th Conference on the Convention on Biological Diversity (COP 16) ended on November 2, 2024, for the time being without making any significant decisions on financing global conservation of species (CBD 2024). At the same time, the scientific community agrees that climate change is further accelerating the extinction of many species (Helmholtz Climate Initiative 2024). Agriculture is particularly at risk, as the global trend towards less diversity in food production and thus a uniformity of nutrition is threatening food security.

In fact, human nutrition is currently based on just a few plant and animal species: of a total of around 7,000 plant species that have been used for human nutrition since the beginnings of agriculture, maize, rice and wheat alone provide over 50 percent of plant calories. Just 12 agricultural crops provide 80 percent of the world's food (Dwivedi et al. 2013) and just three animal species, cattle, pigs and chickens, account for 88 percent of meat production worldwide (FAO 2020).

We need genetic diversity in both plants and animals, otherwise the development of new varieties that are urgently needed to meet future challenges in agriculture and contribute to food security is in danger. Approximately 7.4 million seed samples or genetic material are already stored in gene banks worldwide, including those of the CGIAR (Consultative Group on International Agricultural Research), which are available for further breeding. However, the long-term preservation of this diversity requires practical use outside gene banks, so that both the diversity of species and traditional knowledge about their cultivation and use are preserved.

Solving nutritional problems with diversity

Genetic resources and biodiversity are needed to solve various food problems worldwide: Not only

1. hunger and malnutrition, but also
2. micronutrient deficiencies, so-called hidden hunger, and
3. overnutrition or overweight and obesity and associated diet-related non-communicable diseases.

Worldwide, 124 countries are struggling with at least two forms of malnutrition, 37 countries – mainly in Africa – even with all three forms of malnutrition (Global Nutrition Report 2020). All this while a balanced and varied diet could be a solution to all three forms of malnutrition. It is also common knowledge which foods are being consumed too sparingly and which are being eaten in excess – and how agricultural production should be adapted to take account of this.

In fact, no region in the world currently meets the recommendations for a healthy diet: low-income countries continue to have the lowest consumption of key health-promoting foods such as fruit and vegetables, while higher-income countries have the highest consumption of foods with significant impact on health and the environment, including red meat, processed meat and dairy products (Global Nutrition Report 2021). Consumption of fruit and vegetables is around 50 percent below the recommended amount of five portions per day, which is regarded as healthy, while in Africa it lies as far as 59 percent below recommendations.

Looking at nutrients where a deficiency is particularly evident, increased consumption of fruit and vegetables could close these gaps, e.g. of vitamin A but also of iron or zinc. Supplying the population worldwide and especially in low-income countries with more and more varied fruit and vegetables all year round is a major challenge – especially as post-harvest and processing losses continue to receive too little attention and support in research, development and politics.

A wealth of nutrient-rich, unexplored species

In sub-Saharan Africa, for example, there is a great wealth of indigenous fruit and vegetable species that have been little researched to date and have been partially displaced in cultivation by newly introduced species that are exotic to the region (Kehlenbeck et al. 2013). A project in the arid regions of northern Kenya determined the nutrients in local vegetables and fruit, most of them collected in the wild. It was found that local dark green leafy vegetables in particular had significantly higher levels of iron than white cabbage, which is regularly recommended and promoted as a vegetable in the region.

Examining women who were interviewed for the study and who had integrated wild vegetables and fruits into their diet, it was demonstrated that they were able to absorb significantly higher amounts of iron and zinc, as well as several vitamins (Oduor et al. 2024). These results were shared at a workshop with local politicians, some of whom were surprised at the high nutrient values of their local products and strongly supported further research into the nutrient content of local plants.

Another project in East Africa looked at the year-round availability of fruit and vegetables through resource-efficient processing as well as the marketing of processed products and to what extent they can contribute to a balanced diet (FruVaSe project). The focus was on surplus fruit and vegetables that are available but not fully utilized during the season. Much is lost due to limited freshness: guavas rot under the trees in Kenya, for example, while juice is produced from imported fruit. Apart from guava in Kenya, various processing methods were tested for cashew apples in Tanzania, jackfruit in Uganda and three dark green leafy vegetables, resulting in nutrient-rich, safe and long-lasting fruit and vegetable products.

New products tested in nutritional model

Consumers responded to the new products well to very well and were prepared to pay prices that would cover the cost of production. However, consumer acceptance was higher in urban areas than in rural regions (Tepe et al. 2022). Three fruit and three vegetable products were tested in a nutritional model in the diet of women and children in Tanzania to determine whether they could fill various nutritional gaps left by the conventional diet.

Especially during the season with little fresh fruit and vegetables, there was not enough vitamin A and C as well as iron and zinc available – but this could be compensated for by the various processed fruit and vegetable products (dried leaves, cashew apple juice, guava nut bars and jackfruit nut bars). This was possible at least for women, breastfeeding mothers, schoolchildren aged between 6 and 13 years and infants aged one year and older. For children under one year of age, the nutrient gaps could not be filled; here, additional foods are necessary to achieve a balanced diet (Sarfo et al. 2022).

Overall, the FruVaSe project came to a conclusion that once again confirmed that fruit and vegetable consumption in East Africa is far below recommendations and that an active linking of farmers to fruit and vegetable processing facilities is necessary. Furthermore, the definition of “processed food” must be improved and publicised. In the absence of cold chains and safe storage options, processed fruit and vegetable products with high nutritional value play an important role in filling seasonal gaps. However, processed foods are often seen as “unhealthy” in themselves, and there is a risk of confusion with highly processed foods, the consumption of which should indeed be limited or avoided altogether.

Existing classifications of processed foods, such as the NOVA classification, make a clear distinction between the different stages of processing. These classifications and information on how healthy the food is after processing should urgently be integrated into food-based dietary guidelines and nutritional advice (see FAO - Food Based Dietary Guidelines).

Will “opportunity crops” become the crops of the future?

A promising project on forgotten food crops that have great potential – known more positively as “opportunity crops” – was launched last year by the African Union (AU) and the Food and Agriculture Organization of the United Nations (FAO), among others. The question behind the “Vision for Adapted Crops and Soils (VACS) in Africa” is which crops are best suited to ensure a stable and healthy diet in the future in the face of climate fluctuations. The aim is to carry out a holistic assessment of food crops that have already been very well researched (such as maize, cassava, soybeans, tomatoes) in comparison to plants that have been little studied (e.g. millet, black-eyed pea, Bambara peanut) –26 food crops in total initially (Karl et al. 2024).

A holistic evaluation here means that not only biophysical properties of the plants are included in the model, such as drought tolerance, disease resistance or high crop yields, but also economic properties, such as high acceptance by consumers, as well as socio-cultural properties, e.g. that cultivation of the plant can contribute to the empowerment of women. Also taken into account are amounts of important nutrients such as protein, calcium, vitamin A, iron, zinc and folic acid in the plants as well as whether they are available out of season. It is also examined whether significant plant genetic resources are already available for the crop. Environmental properties also play a role, such as how efficiently the plant can use water and nutrients – i.e. whether it requires comparatively little fertilizer to increase yield, or whether it contributes to soil health by improving its properties (Karl et al. 2024).

Taken together, all of these properties provide a holistic picture of each of the 26 crops – a kind of register with maps and diagrams. This clearly shows which plants are well suited for particular climate settings in Africa, even under changing conditions. According to this study, the cereal crop of choice is not maize but finger millet, pearl millet, sorghum or occasionally fonio or teff. While soybeans can be considered for some regions in Africa even under changed climatic conditions, black-eyed peas or vining peas, for example, and in some cases also chickpeas or Bambara peanuts, have much greater potential.

Once again it can be said that food is available – but quite a few plants are underutilized and “forgotten”, even though they have great potential that needs to be realised in a sustainable way. In addition to data on supplied or missing kilocalories, more data is needed on (micro)nutrients and food diversity – and how much of it reaches the consumer – in order to understand in more detail what exactly is expected from agriculture and its products. Neglected food crops (“opportunity crops”) not only contribute to a healthy diet, but also to the resilience of agricultural and food systems, for example by increasing agrobiodiversity. The fact that genetic resources must be preserved for this purpose and that this requires appropriate financial support must be urgently taken into account in further negotiations following COP16.